1. The problem statement, all variables and given/known data A muon of 40MeV is propagating through free space. It decays to an electron, muon neutrino, and electron antineutrino. What is the beta value of the electron? 2. Relevant equations None provided 3. The attempt at a solution I thought I could just take the total energy of the muon, subtract the rest energy the neutrinos from it, and find a possible total energy of the electron. Then I can just convert that to the beta value. Does this sound right? I'm really lost on this. It seems like there could be multiple values for the electron. Is there a "most probable" value?